Colour is usually delivered in thin-walled cans or containers. These cans have often been stored for such a long time or in such an environment, that one or more of the components of the colour separates or sediments in the can. Furthermore it can be desired to tint the delivered colour to a certain nuance before use. Nowadays such tinting is often made by addition of predetermined amounts of predetermined tinting colours to the delivered base paint, which has a precisely set nuance, and the result will be a well predeterminable colour nuance.
In said examples, the content of the can must be carefully agitated or mixed before the paint can be used for a painting operation.
The paint content of the can container can of course be homogenized or mixed thereby that the lid is taken or from the can, and the paint is agitated by means of a stirring stick or a motor-driven agitator of the kind which comprises a rotatable shaft with an impeller. However, such a paint agitation is not always completely reliable, and an apparatus for carrying into effect such paint agitation (see U.S. Pat. No. 4,095,288, U.S. Pat. No. 4,112,518, GB 1,348,603 and GB 2,062,481) has a number of disadvantages which make them unacceptable for industrial use, for agitation or mixing of paint. Among said disadvantages, it could primarily be mentioned, that the stirring stick or mixer becomes stained with paint, and that if present, an apparatus detail which covers the opening of the paint container, becomes stained with colour and therefore must be cleaned between different mixing operations. Other disadvantages are that at least some of the known apparatuses have an own vessel for the paint, and this means that the apparatus vessel must be cleaned between mixing operations with different paint colours, and furthermore the paint container (can) must be carefully emptied in connection to the transfer of the content thereof to the apparatus vessel, and then, of course, the apparatus vessel must also be carefully emptied after the mixing operation. In the extent the known apparatuses have an apparatus lid for closing the container or the vessel, this lid must also be cleaned between the mixing operations, and in the extent the known apparatuses do not have such a lid, there is severe risk that paint is thrown around during the mixing operation. A common feature for the above mentioned group of known apparatuses for mixing of paint or the like by stirring the paint by means of a stirring stick or the like, is that the mixing operations require long time and are labour intensive, especially in view of necessary cleaning work.
Therefore, since long time ago, a mixing apparatus of the type revealed in see GB 1,586,953 has been utilized in industrial applications. Such a mixing apparatus has among other things the advantage to offer an agitation of the paint in a closed can, that is the can in which the paint is delivered from the factory, without the need of agitation sticks or the like, and the can is closed with its lid. However also apparatus of this type have some disadvantages.
In order that an apparatus of the type at issue shall be industrially acceptable, it must be adaptable to differently container sizes and different paint amounts in a relatively wide interval, for example cans from one liter to five liters. Such cans or containers have various designs depending on producer, but usually they consist of thin-walled tin containers which usually have the shape of a right circular cylinder. If the apparatus subjects the can for shaking movement which has substantial movement components across the axial direction of the can, it is necessary to strongly clamp the can axially in order to prevent the can from becoming displaced in said cross direction. For practical reasons, the clamping is arranged between parallel clamping plates, because the apparatus must be able to cope with cans of very differently sized and shaped cross-section areas. In any case the can clamping force is delimited by the low strength of the can.
Another disadvantage with the machine according to GB 1,586,953 is that the shaking movement occurs in a single plane, and this means a risk for insufficient agitation of the content of the can in directions which intersect said plane.
It is true that machines are known at which the can is orbited in a circular path with large radius, and at which the can simultaneously it rotated with another rotational velocity around its own axis, but such machines require unacceptable space and cannot work with effectively high rpms due to the risk that the can is crushed at required axial clamping in the apparatus.
Another disadvantage with the machine known from GB 1,586,953 is that the transfer of power of from the drive engine of the apparatus into paint stirring power, is relatively low.
An object of the invention is therefor to provide an apparatus which maintains the advantages of apparatuses of the type which is known from GB 1,586,953, and which reduces or eliminates the disadvantages of the known apparatus type.